Luminaire and methodologies for combined visible illumination and deactivation of bacteria

ABSTRACT

An example luminaire includes a white light source (e.g. LEDs emitting white light in a region of the CIE color chart within three Macadam ellipses below the black body curve) and a violet light source emitting light in a wavelength range of approximately 380 nm to 450 nm (e.g. 405 nm LEDs) for deactivating bacteria, such as Methicillin-Resistant  Staphylococcus Aureus  (MRSA) on a surface exposed to illumination from the luminaire. A controller coupled to the sources pulses the violet light source at periodic intervals or at random times. When ON, the violet source emits light for deactivating bacteria at an intensity higher than the concurrent intensity of the white light.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/631,063, filed Feb. 15, 2018, entitled Luminaire and Methodologiesfor Combined Visible Illumination and Deactivation of Bacteria, thedisclosure of which is entirely incorporated herein by reference.

TECHNICAL FIELD

The examples discussed herein relate to luminaires, lighting systemsand/or lighting techniques for providing a combination of light forgeneral illumination and light for deactivating a bacteria.

BACKGROUND

In recent years, there have been various proposals to incorporate, ingeneral lighting equipment, light sources specifically configured todeactivate bacteria on a surface, such as Methicillin-ResistantStaphylococcus Aureus (MRSA) on work surfaces, sinks, floors etc. ofhospitals, nursing homes or the like. Some proposals have used a singlesource to generate somewhat white light and light specificallyconfigured to deactivate bacteria, in a manner such that the combinedlight is suitable for general illumination. Other proposals haveincorporated white light sources and disinfection light sources togetherin one luminaire, including some implementations with independentintensity control of the two different types of sources. However, thereis room for still further improvement.

SUMMARY

The examples combine white light from a first source and cleansing lightfrom another source in one luminaire. The cleansing light is pulsed. Forexample, during each pulse emission, the output of the cleansing lightmay exceed intensity of concurrent white light emission.

For example, a disclosed system may include a luminaire and acontroller. The luminaire includes a white light source, for generalillumination, and a cleansing light source. The cleansing light sourceis configured to emit visible cleansing light of one or more wavelengthsthat deactivate a bacteria. The cleansing light source also is arrangedso that emitted cleansing light is combined with the white light fromthe white light source. The controller is coupled to the light sourcesof the luminaire to control light emission from the white light sourceand light emission from the cleansing light source. The controllercauses the cleansing light source to emit pulses of visible cleansinglight at pulse times during white light emission from the white lightsource. During each pulse time of emission of a pulse of cleansing lightfrom the cleansing light source, the controller controls the sourcessuch that the intensity of pulse emission of the cleansing light fromthe cleansing light source is higher than the intensity of the whitelight emission from the white light source.

A method example may involve emitting white light from a first source ina luminaire. During the white light emission, the method also includesemitting pulses of visible cleansing light of one or more wavelengthsthat deactivate a bacteria, from a second source in the luminaireseparate from the first source, for combination with the white lightemission. During each pulse time of emission of a pulse of cleansinglight from the second source, the intensity of pulse emission of thecleansing light from the second source is higher than the intensity ofthe white light emission from the first source.

In some more specific examples of a system or a method, the spectrum ofthe cleansing light has a maximum peak at a wavelength in a range of 380nm to 450 nm. The white light may be within three Macadam ellipses belowthe Plankian Locus (black body curve) of the CIE color chart.

One or both of the light sources may be adjusted or otherwise controlledin response to one or more inputs. For example, a range sensor mayenable the controller to adjust the intensity of pulse emissions of thecleansing light from the cleansing light source based on the detectedrange. By way of another example, use of an occupancy sensor may enablethe controller to adjust the intensity of pulse emissions of thecleansing light from the cleansing light source based on detectedoccupancy/non-occupancy state. In yet another specific example, thecontroller is further configured to adjust one or more of ON/OFF stateof combined light emission from the luminaire, the intensity of pulseemission of the cleansing light from the cleansing light source, or theintensity of the white light emission from the white light source, inresponse to an input received via the user interface.

Several specific examples of different techniques for controlling thecleansing light relative to the white light also are disclosed below.For example, the intensity of the white light emission from the firstsource may be maintained at least substantially constant over a timeinterval including emissions of a number of the pulses of the cleansinglight from the second source. As noted, the cleansing light pulses,however, have intensity greater than the intensity of the white light.

In another example, the intensity of the white light emission from thefirst source is maintained at least substantially constant over eachperiod between cleansing light pulse emissions from the second source,at a level sufficient for a desired degree of white light generalillumination. However, at times of cleansing light pulse emissions fromthe second source, the intensity of the white light emission from thefirst source is lowered to a non-zero level such that combined emissionsof white light and cleansing light are at a level sufficient for adesired degree of general illumination.

In a further example, one or more of the number of pulses, the pulseduration, or the pulse amplitude, of the cleansing light pulse emissionsfrom the second source, over an interval of time, are controlled so thattotal cleansing light emission over the interval achieves a dosageexpected to be sufficient to deactivate bacteria on a surface exposed tothe pulses of cleansing emission.

Additional objects, advantages and novel features of the examples willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing and the accompanying drawings or may be learned by productionor operation of the examples. The objects and advantages of the presentsubject matter may be realized and attained by means of themethodologies, instrumentalities and combinations particularly pointedout in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accordancewith the present concepts, by way of example only, not by way oflimitations. In the figures, like reference numerals refer to the sameor similar elements.

FIG. 1 is a simplified functional block diagram of a system forproviding general illumination with bacteria cleansing light.

FIG. 2 is a plan view showing use of a luminaire of the type used in thesystem of FIG. 1 to provide combined general illumination and cleansinglight in a room.

FIG. 3 is a plan view showing use of a number of luminaires of the typeused in the system of FIG. 1 to provide combined general illuminationand cleansing light in a room.

FIG. 4 is a functional block diagram of a networked set of lightingsystems with most of the elements of each lighting system incorporatedin the luminaires with the light sources and showing several other typesof intelligent elements that may communicate with such lighting systems.

FIG. 5A is a simplified illustration of the CIE 1931 color chart usefulin explaining color aspects of the light from the cleansing light sourceand the white light source in the luminaire of the system of FIG. 1.

FIG. 5B is an enlarged view of a section of the color chart of FIG. 4,overlaid to help illustrate a more detailed example of the colorcharacteristic light from the white light source in the luminaire of thesystem of FIG. 1.

FIGS. 6 to 9 are various relative intensity diagrams showing variousexamples of intensity and timing relationships between white lightemissions and cleansing light emissions from a luminaire or a system ofluminaires.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples in order to provide a thorough understanding ofthe relevant teachings. However, it should be apparent to those skilledin the art that the present teachings may be practiced without suchdetails. In other instances, well known methods, procedures, components,and/or circuitry have been described at a relatively high-level, withoutdetail, in order to avoid unnecessarily obscuring aspects of the presentteachings.

The examples below relate to improved hardware and techniques forcombined general illumination and illumination with a cleansing light,that is to say, a light of a spectral characteristic expected todeactivate one or more types of bacteria. In a simple example, a systemmay include a luminaire and a controller. The luminaire includes a whitelight source and a separate cleansing light source. The controller maybe incorporated in the luminaire or separate from the luminaire.Systems, however, may include some number of luminaires controlled byone controller or systems involving a number of networked controllersand luminaires associated with or incorporating the controllers.

The term “luminaire,” as used herein, is intended to encompassessentially any type of device that processes energy to generate orsupply artificial light, for example, for general illumination of aspace intended for occupancy or observation, typically by a a human thatcan take advantage of or be affected in some desired manner by the lightemitted from the device. However, a luminaire may provide light for useby automated equipment, such as sensors/monitors, robots, etc. that mayoccupy or observe the illuminated space, instead of or in addition tolight provided for a human. In most examples, the luminaire(s)illuminate a space or area of a premises to a level useful for a humanoccupant in or passing through the space, e.g. general illumination of aroom or corridor in a building or of an outdoor space such as a street,sidewalk, parking lot or performance venue.

The illumination light output of a luminaire, for example, may have anintensity and/or other characteristic(s) that satisfy an industryacceptable performance standard for a general lighting application. Theperformance standard may vary for different uses or applications of theilluminated space, for example, as between residential, office,manufacturing, warehouse, hospital, nursing home, or retail spaces.

Terms such as “artificial lighting,” as used herein, are intended toencompass essentially any type of lighting that a device produces byprocessing of electrical power to generate the light. An artificiallighting device, for example, may take the form of a lamp, lightfixture, or other luminaire that incorporates suitable light sources,where each light source by itself contains no intelligence orcommunication capability, such as one or more light emitting diodes(LEDs) or the like, or a lamp (e.g. “regular light bulbs”) of anysuitable type.

In several illustrated examples, such a luminaire may take the form of alight fixture, such as a pendant or drop light or a downlight, or wallwash light or the like. Other fixture type luminaire mountingarrangements are possible. For example, at least some implementations ofthe luminaire may be surface mounted on or recess mounted in a wall,ceiling or floor. Orientation of the example luminaires and componentsthereof are shown in some of the drawings and described below by way ofnon-limiting examples only. The luminaire with the lighting component(s)may take other forms, such as lamps (e.g. table or floor lamps or streetlamps) or the like. Additional devices, such as fixed or controllableoptical elements, may be included in the luminaire, e.g. to distributelight output from the light source in a particular manner.

Terms such as “lighting device” or lighting “system,” as used herein,are intended to encompass essentially any combination of an example of aluminaire discussed herein with other elements such as electronics of acontroller and/or support structure, to operate and/or install theparticular luminaire implementation. Such electronics hardware, forexample, may include some or all of the appropriate driver(s) for theillumination light source, any associated control processor oralternative higher level control circuitry, and/or data communicationinterface(s). The electronics for driving and/or controlling thelighting component(s) may be incorporated within the luminaire orlocated separately and coupled by appropriate means to the light sourcecomponent(s) of the luminaire.

Light output from the luminaire, lighting device or lighting system maycarry information, such as a code (e.g. to identify a luminaire or itslocation) or downstream transmission of communication signaling and/oruser data. The light-based data transmission may involve modulation orotherwise adjusting parameters (e.g. intensity, color characteristic ordistribution) of the light output from the white light source and/or ofthe light output from the cleansing light source.

It may be helpful to discuss a first system example with respect toFIG. 1. The lighting system 10 in the example of FIG. 1 includes aluminaire 11 and a controller 13. The luminaire includes a white lightsource 15, for general illumination, and a cleansing light source 17.

The white light source 15, in the example, is configured to emit whitelight within three Macadam ellipses below the Plankian Locus (black bodycurve) of the CIE color chart, although in some cases, white lightsources having other white emission characteristics may be used. Avariety of different types of light sources may be used to implement thewhite light source 15. In the example, the white light source utilizesan appropriate number of white LEDs 19 of a type and number typicallyused for general illumination, e.g. for a traditional white light indooror outdoor illumination application.

The cleansing light source 17 is configured to emit visible cleansinglight of one or more wavelengths that deactivate a bacteria. Thecleansing light source 17 also is arranged so that emitted cleansinglight is combined with the white light from the white light source. Avariety of different types of light sources may be used to implement thecleansing light source 17. In the example, the cleansing light source 17utilizes an appropriate number of violet LEDs 21 of a type and numbersuch that pulsed operations thereof over a period or interval of timecan supply an adequate dosage of cleansing light to inactivate bacteria.In the example, the violet LEDs 21 are 405 nm LEDs.

Each LED 19 is rated in the 380 nm to 450 nm range, which is sometimesreferred to herein as violet. An example of a suitable LED that may beused for LEDs 19 is a 405 nm LED. Semiconductor devices such as the LEDs19 exhibit emission spectra having a relatively narrow peak at apredominant wavelength, although some such devices may have a number ofpeaks in their emission spectra. Often, manufacturers rate such deviceswith respect to the intended wavelength of the predominant peak,although there typically is some variation or tolerance around the ratedvalue, from device to device. For example, each LED 19 in the example ofFIG. 1 may be rated for a 405 nm output, which means that it has apredominant peak in its emission spectra at or about 405 nm (within themanufacturer's tolerance range of that rated wavelength value) and emitswavelengths of light in some band around the predominant peakwavelength.

The controller 13 is coupled to the light sources 15, 17 of theluminaire 11 to control light emission from the white light source 15and light emission from the cleansing light source 17. The controller 13causes the cleansing light source 17 to emit pulses of visible cleansinglight at pulse times during white light emission from the white lightsource 15. During each time of emission of a pulse of cleansing lightfrom the source 17, the controller 13 controls the sources 15 and 17such that the intensity of pulse emission of the cleansing light fromthe light source 17 is higher than the intensity of the white lightemission from the light source 15.

In the example of FIG. 1 each source 15 or 17 includes a number of LEDs19 or 21, and the controller 13 utilizes a two-channel LED driver. Anytwo-channel LED driver 23 that provides sufficient controllable power todrive the selected LEDs 19 and 21 may be used. Examples of suitabledrivers 23 are available from eldoLED B.V. One of the control channeloutputs of the driver 23 in connected to drive the LEDs 19 of the whitelight source 15, and the other of the control channel outputs of thedriver 23 is connected to drive the LEDs 21 of the cleansing lightsource 17. Alternative implementations of the sources 15, 17 may haveadditional types of LEDs, e.g. an RGBW implementation of source 15 mayhave four types of independently controllable LEDs, for red (R), green(G), blue (B) and white (W). In such implementations of the luminaire11, the driver 23 may be of a type having additional control channelsfor the additional types of LEDs.

Although not shown, the two channel driver 23 may receive power from ACmains, 100V AC to 488V AC, e.g. 120V AC or 220V AC. The driver 23, forexample, may be a multi-volt input device capable of driving the LEDsusing power obtained from any AC source in a range of 120V AC to 227V.It is also possible to implement the luminaire 11 with low voltage DCpower supply, such as a 24V supply that hospitals utilize for magneticresonance imaging (MRI) rooms in which ferromagnetic materials may notbe permitted in the room with the MRI devices. As another alternative,the luminaire may use a battery power source, as an alternative or abackup to AC mains power. The circuitry of the device 10 may be locatedremotely from the luminaire 11, so that only the sources 15, 17 areincluded in the luminaire 11, and a remotely located driver 23 wouldconnect to the LEDs 19, 21 to supply controlled current to drive theLEDs 19, 21.

The driver 23 in the example is directly responsive to an input from auser interface device 25 and exchanges data with a processor, which inthe example is a microcontroller unit (MCU) 27 although a microprocessoror other type of processor circuitry may be used. In an implementationusing an eldoLED driver as driver 23 of the system 10, the driver maysupply DC power to the user interface device 25. The user interfacedevice 25 may be a simple switch, a dimmer, a keypad, touchpanel etc.Depending on the implementation of the user interface 25, the controllermay be configured, for example, to adjust one or more of ON/OFF state ofcombined light emission from the luminaire 11, the intensity of pulseemission of the cleansing light from the cleansing light source 17, orthe intensity of the white light emission from the white light source15, in response to an input received via the user interface 25. In otherimplementations using different types of drivers, the MCU may receiveinput from the user interface device 25 and control the driver 23 basedon the received inputs.

The white light source 15 may be a fixed output device, or the source 15may be dimmable from full ON to full OFF. The violet cleansing lightsource 17 is pulsed ON/OFF in accordance with a control algorithm,rather than being constantly ON at a particular level. The controller 13in the example can vary the amplitude, frequency, time duration orwidth, phase or the like of the pulses of violet cleansing light outputby the source 17. Such parameters of the pulses are controlled toachieve an average energy of the emitted cleansing light over a periodof time, e.g. to achieve dosage of the cleansing light sufficient todeactivate a bacteria within range of the emission after passage of theperiod of time. The controlled pulse parameters may be constant over theperiod of time or may vary over the period of time algorithmically or inresponse to sensed conditions such as room occupancy or ambient lightlevel. For example ten pulses of a timeframe having a long pulse ONduration may deliver the same average energy as 50 pulse o shorter ONduration in the same timeframe.

The driver 23 could be a relatively simple device, mainly with circuitryto selectively provide two control channel outputs with the minimumlevel of variability to implement a particular one of the cleansing andillumination algorithms described below based control from a higherlevel control element of the system, such as the MCU 27 in the example.Other driver implementations, such as intelligent drivers available fromeldoLED, include more sophisticated driver circuitry as well as someinternal logic circuitry and can support a wider range of modulationoptions selectable in response to commands from an MCU or other higherlevel logic circuit of the system 10.

In an LED based implementation of the luminaire 11, the LEDs 19 and theLEDs 21 may be mounted on one or more circuit board housed within theluminaire 11. In many cases, the LEDs 19 and the LEDs 21 will be on onecircuit board, for example, intermingled at various locations on theboard. The luminaire 11, however, may have separate circuit boards forthe LEDs 19 and the LEDs 21, and/or may use two or more circuit broadsfor one or both sets of LEDs. The particular circuit boardconfiguration, for example, may be adapted to the desired form factor ofthe luminaire 11 and/or to optimize heat dissipation from the LEDs 19and the LEDs 21.

An MCU like that shown at 27 typically is a microchip device thatincorporates the actual processor circuitry in the form of a centralprocessing unit (CPU) 29 along with various memories 31 for storinginstructions for execution by the CPU 29 as well as data having beenprocessed by or to be processed by the CPU 29, and input/output ports(I/O) 33 for suitable connection/communication of the MCU 27 with othersystem elements. The example MCU also implements a clock (Clk) 34 fortiming related functions. The clock 34 may be a specific circuit withinthe MCU 21 or implementing as a program controlled function of the CPUprocessor 29.

The CPU, any circuitry of the clock, the memory and the I/O of the MCU27 typically are all included on a single chip and sometimes referred toas a “system on a chip” or SoC. Although shown separately, the elementsof the MCU 27 may be incorporated on a chip with the two-channel LEDdriver 23 and/or with circuitry of a network communication interface 35.The memory 31 for example, may include volatile and non-volatilestorage; and the program instructions stored in the memory 31 mayinclude a lighting application (which can be firmware), in this example,for implementing the processor functions of the controller 13 relatingto controlling the white light output and cleansing light output fromthe luminaire.

The example represents an arrangement in which one controller controls asingle luminaire 11. FIG. 2 is a plan view showing use of a luminaire 11of a system like the system 10 of FIG. 1. As shown in FIG. 2, theluminaire 11 provides combined general illumination and cleansing lightin a room.

The system 10, however, may be easily modified to include and control alarger number of such luminaires. FIG. 3 is a plan view showing use of anumber of luminaires 11 arranged in a ceiling or the like to providecombined general illumination and cleansing light in a room. There are anumber of ways that a system 10 might be configured to have and controla number of luminaires 11, such as in an application like that of FIG.3.

For example, the LED driver 23 (FIG. 1) may be expanded to provide twocontrolled drive channel outputs to the LEDs of the sources in each ofone or more additional luminaires 11. In the example, the driver 23 isin the controller 13, which may be separate from the luminaire 11. In analternate approach for unified processor control of a larger number ofluminaires 11, each luminaire may include a two-channel LED driver, andone MCU or the like may control two or more such driver-integratedluminaires. It should also be apparent that the driver and MCU of thecontroller 13 and possibly the communication interface 35 may beimplemented within the luminaire 11.

The communication interface 35 may be any communication device suitablefor lighting related local communications between the system 10 andother similar systems, with common control equipment such as wallcontrollers or on-premises servers or gateway, or even with an externalwide area network (WAN). The communication interface 35, for example,may be a network access card supporting wired connectivity over a datanetwork, such as Ethernet, or may be a wireless transceiver compatiblewith a standardized wireless communication protocol, such as WiFi,Zigbee, personal area network (PAN) e.g. in the 900 MHz band, Bluetoothor Bluetooth Low Energy (BLE), LiFi, etc.

Network communications, for example, may allow operation of aneighboring number of luminaires (e.g. like in FIG. 3) for each of somenumber of zones in a large space, in a coordinated way to implement acleansing and illumination algorithm of the type described herein. Someareas of the zone would have overlapping exposure from two or moreluminaires, e.g. between adjacent luminaires or in the center of thearea, whereas other areas of the zone around the periphery may havelittle or no overlapping exposure and receive light only from one of theluminaires. In such a scenario, the network communications allows theMCU or MCUs that control the luminaires of a particular zone to adjustoperations of the various cleansing sources, e.g. to optimize cleansinglight uniformity as much as feasible while insuring that all areas ofthe zone receive at least the minimum amount for the disinfectiondosage.

Bacteria are sensitive to an overall applied energy of the cleansinglight. The overall energy is a function of both intensity andaccumulated ON time. Stated another way, the bacterial elements areeffected by both a total time duration by the cleansing light and theamplitude or level of the cleansing light exposure. For example, iftimeframe of 1 with an exposure amplitude 10 kills the exposed bacteria,it is reasonable to assume that an exposure of amplitude 5 kills theexposed bacteria after exposure for a timeframe of 2 or that exposure ofamplitude 20 kills the exposed bacteria after exposure for a timeframeof 0.5. The controller 13 in the example can vary the amplitude,frequency, time duration or width, phase or the like of the pulses ofviolet cleansing light output by the source 17. Such parameters of thepulses are controlled to achieve an average energy of the emittedcleansing light over a period of time, e.g. to achieve dosage of thecleansing light sufficient to deactivate a bacteria within range of theemission after passage of the period of time.

The pulsing of the violet cleansing light from source 17 spreads theexposure duration. The pulsing also takes some of the violet componentout of the combined light emitted from luminaire 11 to illuminate thespace, e.g. so that the combined output light does not necessarilyappear as violet in hue to a person occupying the illuminated space. Thepulse rate, however, is fast enough that the human eye response does notcause the person to observe the pulsing as a perceptible flicker. Forexample, the pulsing may be at a rate higher than the typical humanflicker fusion frequency, e.g. 30 Hz, 60 HZ, or 120 Hz or higher. Pulsefrequencies of 70 HZ or higher are preferred although the upper end ofthe range may be relatively high, e.g. 800 HZ to 1,000 Hz or to 20,000HZ or higher. As shown by way of several algorithms discussed in moredetail later, the controller configuration allows considerableflexibility as to the manner in which the appropriate dosage ofcleansing light is delivered within the particular time period.

When adjusting the overall light intensity of the combined light outputfrom the luminaire 11, both white and cleansing types of light can beindependently controlled. For example, the white may be dimmed withlittle or no concurrent dimming of the violet cleansing light from LEDs21. If dimming lowers the intensity of the white too much withoutdimming the violet cleansing light, however, an increased relativeviolet component may make the overall illumination more violet andtherefore less desirable to a human occupant. Such a result may beacceptable if desired to insure continued cleansing. At other times, itmay be preferable to dim or turn OFF the violet light to maintain colorquality of the relatively white luminaire output light, e.g. during aperiod when the desire for quality illumination outweighs the need forconcurrent cleansing (as opposed to cleansing at a later time).

Returning to FIG. 1, output of one or both of the light sources 15, 17may be adjusted or otherwise controlled in response to one or moresensed conditions. For that purpose the example system 10 of FIG. 1 alsooptionally includes one or more sensors 37.

A range sensor 39 may enable the controller 13 to adjust the intensityof pulse emissions of the cleansing light from the cleansing lightsource 17 based on the detected range, e.g. to the floor or a countertopsurface or the like to be cleansed. The sensor 39 may be located in ornear the luminaire to measure range of a surface or occupant from anoutput of the luminaire 11, from a ceiling or other surface on which theluminaire 11 is mounted, from a height of the luminaire 11 as mounted onor below a ceiling, or the like. The range sensor 39 may be a laserrange finder, a radar device, a sonar device, an infrared emitter anddetector aligned with a retroreflector at the surface to be sensed, astereoscopic camera system or the like. An alternative to the rangesensor 39 might use a camera to sense the amount of cleansing lightreflected from different areas of the illuminated space.

If the system 10 does not include a range sensor, the system 10 mayconfigured as part of the commissioning of the system at a particularinstallation, based in part of range determinations. The rangeinformation, instead of coming from a sensor in the system, would beseparately provided, for example, from a commissioning device (notshown) in communication with the system 10 based on measurements done byor otherwise provided to the commissioning device. Various measurementand programming techniques may be used in commissioning, including toinput data regarding range from the luminaire 11 to one or more surfacesto be cleansed by light from source 17. The range set-up as part of thecommissioning process eliminates the added cost of the range sensor 39;but such an implementation of the system 10 is less dynamic, e.g. achange in room arrangement that changes the range to the surface maynecessitate a new configuration operation by a technician or the like toadjust the range setting of the system.

Hence, the range sensor 39 (or a commissioned range setting) provides anindication of the distance from the luminaire 11 to the surface heightin the room that is to be cleansed by the violet light from cleansinglight source 17. For example, in an examination room, one luminaire 11may be over an examining table whereas another luminaire 11 may be overa tile floor. In a dynamic implementation of system 10, each luminaire11 may have an associated range sensor 39, or the luminaire over thefloor may be set for a standard range, say to that to the floor butthere is a sensor 39 associated with the luminaire over the examiningtable. In such an example, the luminaire over the table is controlledbased on detection of range from the luminaire to the table top, say sixfeet. The system controls the luminaire over the floor based onprogrammed or sensed range from that luminaire to the floor, say ninefeet.

To achieve a particular amount of illumination at a distance from alighting device, e.g. for cleansing in the example, the light outputfrom the luminaire 11 needs to be higher for larger separation distances(or can be lower for smaller separation distances). The variation oflight at each surface may be inversely proportional to the square of thedistance to the relevant surface from the particular luminaire. In theexamination room examples, the system controls the source 17 providingrespective cleansing light outputs of the two luminaires based on thedifferent ranges. Over the period of time for the exposure dosage, thesystem provides a somewhat lower amount of cleansing light (e.g. lessintense, fewer pulses, or shorter duration pulses) in the light outputfrom the luminaire over the examination table than is provided in lightoutput from the luminaire over the floor.

By way of another sensor example, use of an occupancy sensor 41.Although other types of occupancy sensing devices may be used as thesensor 41, a typical example uses a passive infrared (PIR) lightdetector or and associated processing circuitry or radar (e.g. ultrawide band) to determine occupancy status based on detection of motion orlack of motion detection for some set time. The occupancy sensor 41 mayenable the controller 13 to adjust the intensity of pulse emissions ofthe cleansing light from the cleansing light source 17 based on adetected occupancy/non-occupancy state of a space illuminated by thecombined light output from the luminaire 11. The controller 1 may alsocontrol ON/OFF state or intensity of light output by the white lightsource 15.

If the system detects motion in the room, the system may choose tooptimize color quality of the combined relatively white light output ofthe luminaire. For that purpose, the system may reduce (e.g. by half)the amount of violet cleansing light or turn OFF the cleansing lightsource. To compensate, at another time when occupancy or motion is notdetected in the room, the system can increase the intensity and/or pulseduration of violet cleansing light to still achieve the desiredcleansing light exposure dosage by a particular time on a schedule.

With the network communications capability, either one or the other orboth of the sensors may be in or associated with one luminaire 11 andthe sensing results communicated via the network to other luminaires ina particular group or zone.

The example of FIG. 1 mainly depicted a single system/sourceimplementation, although several modifications to control additionalluminaires/light sources were briefly discussed. The combinedillumination and cleansing may be implemented in a variety of othersource and controller implementations, particularly if intended forcoordinated operations and/or monitoring thereof in a largeinstallation, such as a hospital, rehabilitation facility, or nursinghome. FIG. 4 illustrates, in functional block diagram form, a networkedsystem 101 including a set of lighting systems 10A to 10N. In theexample, each of the lighting systems 10A to 10N incorporates most ofthe elements of system 10 of FIG. 1 into each luminaire with the whiteand cleansing light sources. As shown, for example, each luminaireforming one of the lighting systems 10A to 10N includes the two sourcesand the two-channel driver; and each such system 10A to 10N includes amodule incorporating the MCU and the communication interface (Comm).That module, in one or more of the lighting systems 10A to 10Noptionally may incorporate one or more of the sensors discussed aboverelative to FIG. 1.

The system 101 includes a user interface device, which may be a simpleswitch, a dimmer, a keypad, touchpanel etc. In the example of FIG. 4,the user interface device is shown as a wall switch at 25 configured forON/OFF control inputs from the user. Unlike the example of FIG. 1,however, the wall switch 25 is not connected directly to the drivers inthe luminaire but instead is configured for data communications with theluminaires. Although not separately shown, the wall switch 25 mayinclude an MCU and communication module similar to those in theluminaires 10A to 10N except configured to instead respond to and drivethe user interface components (e.g. push buttons and indictor lights) ofthe wall switch 25.

Any suitable data communication technology may be used. The example ofFIG. 4 illustrates an arrangement of system 101 that utilizes wirelessdata communications. For that purpose, communication interfaces in thelighting systems 10A to 10N and the wall switch 25 take the form of oneor more wireless transceivers (including wireless transmitter andreceiver circuitry and circuitry and data connections compatible withthe MCU). Each such component 10A to 10N or 25 will include a wirelesstransceiver for lighting related communications, such as for controland/or operational reporting functions, and those transceivers togetherwill form/operate as a wireless lighting control network 45.

The wireless transceivers and thus the network 45 may utilize thephysical layer and others of the lower layers of a standardized wirelesscommunication protocol, such as WiFi, Zigbee, personal area network(PAN) e.g. in the 900 MHz band, Bluetooth or Bluetooth Low Energy (BLE),LiFi, etc. Higher layers of the protocol stack may be specific tolighting, whether standardized or proprietary to the equipment of aparticular lighting system vendor.

Although not shown, the lighting systems 10A to 10N and the wall switch25 each may include one or more additional wireless transceivers, forbackup communications or for additional communication functions, such ascommissioning or configuration or maintenance.

The system 101 at the premises may be implemented in a standaloneconfiguration, e.g. without gateway access to other systems, networks orcomputers. The example of FIG. 4, however, shows an implementation witha gateway 50 providing access to a wide area network (WAN) 55, such asan intranet or the Internet, outside the premises. The gateway 50 andWAN 55 provide network data communications access to other computers,such as user terminal 60 or server computer 65, for interactions thereofwith one or more of the lighting systems 10A to 10N and/or the wallswitch 25. The gateway 50 may have a network link at the premises toluminaires and wall switches of other systems 101 at the premises or maylink via WAN 55 to/through other gateways with wireless networkcommunications to luminaires and wall switches of other systems 101 atthe same or other premises.

The example shows a single grouping of luminaires 10A to 10N and one ormore standalone wireless user interface devices shown as wall switch 25Aon the wireless network 45. There may be other similar groups on thesame wireless network 45, e.g. if all other groups are located withinrange of the one gateway 50. The dotted line cloud in the drawingrepresents an additional wireless network similar to network 45, whichwould link one or more similar groups of luminaires and wall switches orthe like at the premises to each other and to another gateway (not shownseparately) within wireless range of the equipment of the additionalgroup(s).

More information about an implementation of a networked system likesystem 101 of FIG. 4 may be found for example in U.S. Pat. No. 9,820,361by Turvy, Jr., et al.

The particular examples utilize 405 nm LEDs 21 for the emitters of thecleansing light source 17 and white LEDs as the LEDs 19 of the whitelight source 15 to provide white light of a color characteristic, e.g.within three Macadam ellipses below the Plankian Locus (black bodycurve) of the CIE color chart. A controller coupled to the sourcespulses the violet light source 17 at periodic intervals or at randomtimes. When ON, the violet source 17 emits light for deactivatingbacteria at an intensity higher than the concurrent intensity of thewhite light.

Exposing bacteria to violet light, in the 380 nm to 450 nm wavelengthrange, has previously been shown to deactivate bacteria. Usingvisible-wavelength light, such as in the violet region, is less harmfulto humans or animals than using ultraviolet light, therefore violetlight can be applied in a range of disinfection applications, such asdisinfection of potential contact surfaces. The systems and operationalmethodology examples disclosed herein offer one or more improvementsover prior technologies, some of which are outlined below.

A prior approach utilized a 405 nm illuminator only, and apparently didnot also support general white light illumination. While this may besuitable for applications using the cleansing light only, e.g. involvingdirect application to a surface or material to be cleansed, use in aspace that may need general illumination would require one or moregeneral illumination type light devices in addition to the 405 nmdisinfection device, which is not desirable in general lightingapplications. Such an installation tends to be expensive and complex.The use of two light sources in one luminaire for the two differenttypes of light, as in the examples discussed herein, improves over sucha cleansing only source approach because the luminaire can provide boththe disinfection and general illumination in one fixture or the like.Lighting designers and end users generally prefer ancillary lightingfunctions to be combined with the artificial lighting source in onefixture, so as to avoid the need to install additional luminaires forthe special purpose function, for disinfection in this case.

Another prior approach implemented cleansing and general illuminationwith a single integrated source in the lighting device, such as an LEDwith a 405 nm chip together in one package with a phosphor to convertsome of the 405 nm light to broader band visible light for combinedwhite output. The efficiency of the single source is rather low, e.g.about 35-40 lumens per watt, whereas general illumination LED sourcestoday offer an efficiency of 150 lumens per watt or higher. The twosource approach herein may take advantage of the more efficient whitelight type source, and therefore is more acceptable for general lightrequirements that often are sensitive to commercial or governmentspecified power requirements.

Also, with the single source approach, the ratio of white light toviolet light is fixed based on the design of the source device. There isno way to independently control the cleansing light intensity relativeto the white light intensity. For example, increasing output intensityfor a desired higher level of general illumination may result in anunnecessarily higher or over exposure intensity of the cleansing light.If a fixture with this type of source is mounted too high above thesurface to be cleaned, e.g. higher than the design specification, thefixture may not adequately expose the surface to cleansing light andthus may not effectively disinfect the surface as intended. The use oftwo light sources in one luminaire for the two different types of light,as in the examples discussed herein, improves over such a single sourceapproach because the respective levels of the cleansing light and thewhite light may be independently controlled for different installationconfigurations, for different uses/conditions of illuminated spaces,etc.

Another prior proposal suggested use of a 405 nm source and anotherlight source of light of wavelengths that are perceived as white light,but the white light source always emitted light at a higher intensity orilluminance than the cleansing light from the 405 nm light source. Thisrestriction limits the ability to independently control the intensity ofthe two different types of light to achieve both effective disinfectionat the surface level and variable degrees of general illumination overtime. The techniques in the examples herein may independently vary theintensities of both types of light, and the pulse emission of thecleansing light may have an intensity above the white light intensity,which may allow more efficient operations for both general illuminationand disinfection. Also, the techniques in the examples herein may bemore readily adaptable, e.g. for dimming or other overall control, basedon detected range to a surface to be cleansed, based on a preset orreal-time detection of occupancy, etc.

The examples may include white light LEDs or the like emitting whitelight in a range from 2200° K to 8000° K. The LEDs 19 or other emittersof the white light source 15, in some examples, emit light at least oneMacadam ellipse below the Plankian Locus, although the range may be fromat or just below that curve to as much as three Macadam ellipses belowthe Plankian Locus. Humans tend to perceive white light that is one tothree Macadam ellipses below the Plankian Locus, particularly in a rangeof 2700° K to 5000° K, as white and pleasant with a warmer tone due to amagenta component. Light above the Plankian Locus is perceived assomewhat blue or greenish and thus colder to the human observer.

An example of the combined lighting implementation of a system 10 orexamples of similar systems 10A to 10N in a networked implementation mayuse LEDs or other light emitters of light of particular characteristics.In several examples, with reference for convenience to FIG. 1, thecleansing light source 17 is a violet light source emitting light in awavelength range of approximately 380 nm to 450 nm (e.g. 405 nm LEDs)for deactivating bacteria. The white light source 15, for example, mayuse LEDs or other types of emitters configured to emit white lightwithin three Macadam ellipses below the Plankian Locus (black bodycurve). It may be helpful to explain these parameters of the lightoutputs from the sources in somewhat more detail.

FIG. 5A is a chromaticity diagram, in this example, a simplified versionof the CIE 1931 color chart. In FIG. 5A, the horizontal x axis and thevertical y axis correspond respectively to the x, y chromaticitycoordinates of a given point. Points along outline 200 correspond tocompletely saturated colors ranging from 360 to 700 nm, going clockwisefrom the bottom of the plot (around x=0.18, y=0) around to the righthand corner point (around x=0.73, y=0.26). The line connecting these twopoints represents a range of purple.

A curve 210 within outline 200 is the Plankian Locus, often referred toas the black body curve, of the CIE color chart. The Planckian locuscorresponds to the peak wavelengths of distributions that are emitted byblack bodies at correlated color temperatures (CCT) ranging from low,e.g., less than 500° K at the point labeled 222, to infinitely high, atthe point labeled 224. A portion of the Planckian locus, e.g., colortemperatures from around 2700° K to 6500° K generally corresponds tocolor perceived by humans as “white.”

The cleansing light is a violet light in the range of 380 nm to 450 nm,along the lower left curve of the perimeter of the chart. The examplecleansing source uses 405 nm LEDs. A particular cleansing light emissionincludes wavelengths of light at and around the particular nominalwavelength of the source, e.g. at and around the point corresponding to405 nm.

The light from the white light source 15 is near a portion of thePlanckian locus having a nominal color temperature in the range fromaround 2700° K to 6500° K. FIG. 5B represents an enlarged portion of thecolor chart of FIG. 5A including a section of the Planckian locus. Fordiscussion purposes, we will consider an examples in which the whitelight source 15 emits light near the 2700° K point on the curve 210 oremits light near the 4000° K point on the curve 210.

In FIG. 5B, a central line passing through the curve at a point on thecurve for 2700° K represents color coordinates that generally providethe 2700° K color temperature; and a central line passing through thecurve at a point on the curve 4000° K represents color coordinates thatgenerally provide the 4000° K color temperature. Distance from such apoint on the blackbody curve may be measured as a difference ordifferential (Δ) in the ′u and ′v coordinates, sometimes referred to asΔuv. Above the black body curve, the Δuv is positive; and if largeenough, light on a particular CCT line may be perceived by a humanobserver as somewhat greenish white. Below the black body curve, the Δuvis negative; and if large enough, light on a particular CCT line may beperceived by a human observer as somewhat magenta white.

A Macadam ellipse is a region on the color chart within which colors areindistinguishable from the color at the central point of the ellipse, tothe eye of an average human observer. Macadam ellipses, however, changein size for different regions of the color chart. Generally, people seeat most minor differences from a point on the black body curve if theactual color point of the light is within three Macadam ellipses of thepoint on the black body curve. In the example systems of FIGS. 1 to 4,the light from the LEDs 19 may be at a particular point on the PlankianLocus (black body curve) of the CIE color chart or even above the curve.In many cases described herein, however, the white light is at mostthree Macadam ellipses below the Plankian Locus (black body curve) ofthe CIE color chart.

Light below the black body curve, but within three Macadam ellipses ofthe curve, may be perceived as somewhat warmer white light than lightjust above the curve. Also, the added perception of warmth, helps tooffset the cool perception of violet light during times when the violetcleansing LEDs 21 are operational.

The discussion of the color characteristics of the white LEDs 19, hererefers to the overall light produced by the collection of white LEDs 19.Since light is additive, the group or set of LEDs may include LEDs oftwo or more different types with different characteristics. In such acase, however, the LEDs together would produce a white light output ofthe type described above, e.g. within three Macadam ellipses below thePlankian Locus (black body curve) of the CIE color chart. Also, thewhite source may be implemented with various combinations of LEDs orother sources that combine to produce the white light of the characterdescribed here, such as LED combinations of RGB, RGBA, RGBW, RGBAW,etc., or incandescent or other suitable types of light sources.

The driver 23 may be a circuit capable of providing a controllableconstant current on each output channel to drive the respective sets ofLEDs 17, 19. The current outputs of the two channels are controllableindependently of one another. The MCU 27 or other higher level logiccircuit instructs the driver to vary the outputs from the channels ofthe drivers and thus the current ratio and intensity ratio of cleansingto white light in accordance with an algorithm or operating procedure,several examples of which are described in more detail later. In theexamples of combined illumination and cleansing, at least the drivecurrent for LEDs 21 forming the cleansing source 17 is pulsed to providea controllable pulsed cleansing light output from the luminaire 11. Thedrive current supplied to the white light source 15 and thus the whitelight output from source 15 may be relatively constant or may be pulsedin a controlled manner.

The system may implement an algorithm, for example, by appropriateprogramming and data stored in the memory 31 for execution and dataprocessing by the CPU 29. The algorithm, for example, may monitor thetime each luminaire is ON. The ON/OFF state of the luminaire and/or thedimming state of the luminaire output may be selected by the user, e.g.via a wall controller or an application on a user terminal device. Ifany sensors are provided, the algorithm also monitors the detections ifany by the occupancy/motion sensor or the range sensor.

The duration of an intended disinfection cycle may be any length that isuseful for disinfection control, e.g. one or more hours, one or moredays, a week, or longer or shorter time duration. For purposes of anexample, assume that the intended disinfection cycle time is eachtwenty-four hour day. Disinfection is controlled to achieve a cumulativeexposure within each period of that cycle, reasonably expected todeactivate bacteria. Appropriate dosages are discussed in more detail inthe literature, and the following example is given here for ease ofdiscussion. For the hypothetical example, assume the intended dosage is50% cleansing light output intensity over a total of 10 hours. Omittingunits for simplicity, the cumulative dosage would be the integral overthe cycle time of the intensity, which for constant output intensityover a continuous on-state would just be time multiplied by intensity or10×0.5=5.0 in the hypothetical.

As noted, he MCU 27 monitors the state of the sources 15, 17 of theluminaire 11 and various sensed inputs and uses the clock 34 to monitorand control dosage over time. When the room is unoccupied, the algorithmmay control the 405 nm LEDs 21 of the cleansing light source 17 to havea 50% on time duty cycle of the pulse light output and otherwise drivethe LEDs 21 to their 100% intensity during pulse ON states, whichresults in a cumulative 50% cleansing light output per pulse waveform orper unit time. Assume first that the room remains unoccupied for 10hours. In that simple scenario, the system 10 could achieve the desiredcleansing light dosage of 5.0 cumulative output in 10 hours and may emitlittle if any cleansing light over the rest of the 24 hour cycle whetheroccupied or not. The times of such cleansing light emission while theroom is unoccupied need not be consecutive.

In practice, the room may be used during any given 24 hour day such thatit is only unoccupied for a smaller number of hours of the 24 hour day.The system can compensate by provide some cleansing light duringoccupancy and/or by increasing the duty cycle percentage duringintervals of the day when the room is not occupied, to still achieve theintended cumulative dosage within the 24 hour day.

The clock and timer functions together with the occupancy sensing andknowledge of the controlled drive of the 405 nm LEDs at various timesduring the day enable the MCU 27 to adjust the cleansing light output toadequately provide the intended dosage. For example, when occupied, theMCU 27 may instruct the driver 23 to cause the LEDS 21 to reduceintensity during pulse ON states to 75% and/or reduce the duty cycle ofthe cleansing light pulses, to allow the combination of cleansing lightwith white light from the LEDs 19 to provide a desired quality ofoverall white illumination light. The cleansing light provided duringthe occupied state of the room still contributes towards achieving theintended disinfection dosage during the particular 24 hour day. In sucha day, when the MCU 27 receives an indication that the room is notoccupied, from the sensor 41, the MCU 27 may instruct the driver 23 tocause the LEDS 21 increase intensity during pulse ON states back to 100%and to increase the duty cycle of the cleansing light pulses to 50%, 75%or higher.

During the occupied state, if the user opted to dim the lights, the MCUmay instruct the driver to adjust the ratio of output of the cleansingLEDs 21 to the outputs of the white LEDs 19, to meet the parameters ofthe algorithm for achieving the desired dosage over the 24 hour day. Forexample, if the algorithm indicates that a low cleansing light outputmay not be sufficient, the system can dim the overall light per the userinput but adjust the ratios of outputs to provide a higher amount ofcleansing light per pulse wavelength. This adjustment may degrade thecolor characteristic quality of the combined light, but in this scenariothe algorithm sacrifices some quality of the combined light output forthe improved ability to achieve the cleansing dosage. If the userrequest to dim the lights occurs at a time when the system has alreadyachieved the dosage for the day or is projected by the algorithm to meetthe dosage by the end of the day, the system may opt not to adjust theoutput ratio in favor of the cleansing light and maintain a higheroverall color characteristic quality for the combined output light fromthe luminaire 11.

The intelligent control of the system in our example can implement avariety of different control schemes, for example, for different typesof illuminated spaces. The control scheme, for example, may be differentfor each of an examination room, a hallway, a waiting room and/or apatient's room in different types of care units. If the illuminatedspace is part of a hallway, for example, the algorithm may implement amore deterministic scheme to average the quality of light and averagethe cleansing light parameter(s) over time so that the average cleansinglight will achieve at least the intended dosage for the 24 hour day. Foran examination room, where the quality of the light may be moreimportant to the staff personnel when conducting examinations in theroom, the algorithm used by the MCU would configure the system toprovide at least a minimum level of light quality at all times whenoccupied but to provide a higher cleansing light (e.g. maximum pulseintensity and/or maximum % duty cycle) during all times when the room isunoccupied. For a waiting room that is intended for occupancy onlyduring particular times of day, the algorithm used by the MCU mayconfigure the system to provide a low amount of cleansing light duringscheduled times for occupancy and a higher or maximum amount ofcleansing light during times when the room is scheduled to be closed tobusiness and therefore likely to be unoccupied.

In the examples, the cleansing light output of source 17 is pulsed inresponse to pulse current output from the channel of the driver 23; andthe MCU 27 instructs the driver 23 to vary one or more of the pulseparameters (e.g. one or more of the number of pulses, the pulseduration, the pulse amplitude, the duty cycle, the pulse frequency,etc.) to increase or decrease the amount of cleansing light output fromthe LEDs 21 per unit time (e.g. per second or per minute), such thattotal cleansing light emission over a time interval achieves a dosageexpected to be sufficient to deactivate bacteria on a surface exposed tothe pulses of cleansing emission. The white light output is controlledby the MCU 27 via the driver 23 independently of the control of thecleansing light output. The algorithmic variations outlined above may beimplemented using a variety of pulsing techniques relative to thecleansing techniques in combination with a variety of techniques forcontrolling light output from the white light source.

The combined illumination and cleansing examples discussed herein havesome white light emissions when the system is emitting light from thecleansing light source 17, at least as would be perceived by a person inthe illuminated space. In many examples, the white light is output fromthe LEDs 19 during the ON time of the pulses of the cleansing lightoutput from cleansing LEDs 21 (e.g. in response to a particular level ofa constant current drive signal from the channel of the driver 23). Evenin control scheme examples in which the white light is pulsed, thepulsing of the white light is at a rate above typical flicker fusionfrequencies (similar to the pulse rate of the cleansing light output).As a result, a human occupant would perceive the white light asconstantly ON (free of perceptible flicker), even when the cleansinglight source 17 is OFF.

In these ways, during cleansing light emissions there will always besome perceptible white light component of the output from the luminaire11. When occupied, the combined light may appear as fairly good quality(e.g. high color rendering index “CRI” and/or desirable coordinatedcolor temperature “CCT”), although as noted the quality may becompromised somewhat if the algorithm determines a need to increasecleansing light output to achieve the intended dosage. When unoccupied,the cleansing light output may be increased to more readily achieve theintended dosage, but the system will still supplement the cleansinglight output with a perceptible amount of light from the white lightsource 15, to avoid the impression by a person that may observe the room(e.g. upon entry or passing by an open door or a window into the room)that the room is being intensely decontaminated by violet lightexposure, which might otherwise scare some people as to the danger of abacteria in the room that might otherwise need to be eradicated byextreme treatment or create a fear that the cleansing like includesharmful ultraviolet components. The white light component, however, maybe relatively low during unoccupied times of increased violet lightexposure, for example, the white light output from the source 15 may 5%of the level utilized during normal occupancy/usage of the room.

It may be helpful to consider several examples with regard to the graphsof FIGS. 6 to 9, which illustrate various relative intensities of thetwo components of light output and timing relationships between whitelight emissions and cleansing light emissions from a luminaire or asystem of luminaires. In several of the examples, the cleansing lightpulses are repetitively emitted at a constant rate and constantinterval, over time, to apply a deactivating dosage of the cleansinglight to any bacteria within range of the emissions, although otherpulse parameters may be varied such as pulse duration/duty cycle orpulse intensity (see e.g. FIGS. 6 and 7). For convenience, FIGS. 6 and 7show constant duty cycle but variation in pulse amplitude or intensityin different room states. In other examples the cleansing light pulsesare emitted at random intervals but in sufficient number over a timeperiod to apply a deactivating dosage of the cleansing light a bacteriawithin range of the emission (see e.g. FIGS. 8 and 9). FIGS. 8 and 9also show variation in duty cycle.

With more specific reference to FIG. 6, the intensity of the white lightemission from the first source is maintained at least substantiallyconstant over a time interval including emissions of a number of thepulses of the cleansing light from the second source. The white lightsource 15 can be driven by a constant current output for the particularchannel of the driver 23. For intensity control, the MCU 27 instructsthe driver 23 to increase or decrease the driver current to the LEDs 19of source 15 to increase or decrease the intensity of the white lightoutput.

FIG. 6 shows the first scheme where the white light is constantly ON ata set level, and the system periodically adds a cleansing light pulse.In the occupied state, the white light is at a relatively high constantlevel, and when emitted, the amplitude of the violet light pulses issomewhat higher than the white light output amplitude. In the unoccupiedstate, the white light is still constantly ON but at a lower constantamplitude level. Again, in this second state, the amplitude of theviolet light pulses is somewhat higher than the white light outputamplitude. In the unoccupied state, however, the maximum amplitude ofthe violet light pulses is still higher than in the occupied state. Thecircuitry of the driver 23 may be configured to controllably vary theheight or amplitude of the pulses which corresponds to instantaneouslight output intensity (as shown), or the width of the pulse durationand thus the duty cycle, or the frequency of (and thus the spacingbetween) the pulses, or some other pulse parameter, or combinations oneor more thereof.

In the example, the white light is shown as ON at a constant level forsome time, then changed to a new level that remains constant for sometime, and so on. This type of control may be implemented by controllingthe DC current applied to drive the white light LEDs 19. The violet LEDs21 forming the cleansing light source 17 may be pulsed by turning ON theDC drive current for those LEDs 21 at one power level, at each pulsetime and otherwise turned completely OFF between pulses. The drive ofthe LEDs 19 of the white light source 15, and possibly the violet LEDs21 of the cleansing light source 17, may also be modulated during theintervals when ON at a particular level. The drive of the LEDs 19 of thewhite light source 15, for example, may be pulse width modulated withvariable duty cycles to provide dimming control.

In examples using the constant current control scheme for the whitelight, the white light will consume constant power while ON at aconstant current level. When the system outputs a pulse of the cleansinglight, during the ON time of that pulse, the driver 23 consumesadditional power to also drive the cleansing LEDs 21. If the driver hasa maximum combined output power limit, it may be necessary to limit thepower applied to the white light to reserve some capacity for theadditional driver power needed to generate the cleansing pulses.Although the control aspects that establish the relative amounts oflight output over a period of time are independently controlled, it maybe advantageous to control the relative timing of the pulses of thecleansing light and the white light to reduce the overlap of the whiteand cleansing pulse maximums to reduce the instantaneous powerconsumption. If there is no time overlap of the ON times of the pulsesof the white and cleansing light pulses, and both are completely OFF inbetween pulses, then each channel may utilize the maximum instantaneouspower capacity of the drive4 23. Alternatively, when the cleansingpulses are at maximum, the white light may be ON but at lower amplitude,which still makes more of the driver power available for theinstantaneous cleansing light output.

In the example of FIG. 6, the white light source was driven by constantcurrent to provide a relatively constant intensity output, although thelevel could be changed, e.g. for dimming or the like. FIG. 7 shows thealternative approach in which the white light output may be pulsed aswell and control of the white light output may involve pulse parameteradjustment (e.g. amplitude, duty cycle, frequency, etc.) to increase ordecrease the amount of white light output per unit time. In such anexample, the intensity of the white light emission from the first source15 is maintained at least substantially constant over each periodbetween cleansing light pulse emissions from the second source 17, at alevel sufficient for a desired degree of white light generalillumination. At times of cleansing light pulse emissions from thesecond source 17, the intensity of the white light emission from thefirst source 15 is lowered to a non-zero level such that combinedemissions of white light and cleansing light are at a level sufficientfor a desired degree of general illumination.

FIG. 7 shows the second scheme in which the white light also is pulsed.The white light could be pulsed between a totally OFF state and avariable high/ON state, much like the cleansing light pulses. In theexample, however, the drive current applied to the white LEDs 19 wouldhave a positive direct current (DC) bias; and as a result, the low stateof the pulsed white light does not fall to zero (full OFF) output state.The DC bias may be the same for different room states sensed by thesystem (e.g. occupied versus unoccupied) or may vary in response todifferent sensed room states.

In the example shown in FIG. 7, during ON times of the pulses of violetlight output, the driver supplies some power to the white light source15 based on the DC bias included in the drive channel output connectedto the white LEDs 19. In both the example occupied and unoccupied roomstates, the cleansing light source 17 together with white light source15 provide a combined light output of the luminaire 11 at or slightlybelow the dashed line in the drawing, which corresponds to the outputintensity achievable in response to the maximum power available from thedriver 23.

While the system 10 senses that a room is occupied, when pulsed at ahigh ON-state, the white light output intensity may be at an amplitudelevel at or near the maximum combined output corresponding to themaximum total drive power available from the driver 23, as representedby the dashed horizontal line in the drawing. In the unoccupied state,the high state of the white light output may be substantially lower thanin the occupied state. In the occupied state, the white light intensityis reduced during the ON time of the violet pulses to a levelcorresponding to the DC bias of the applied drive current, as shown.Although the white light pulsing may be fully OFF during violet lightpulse emissions, as shown, the lower level white still provides somewhite light output during violet light pulse emissions. In this case,the violet cleansing light pulse emission is at a higher level than thewhite light emission, during the ON times of the pulses of violet lightoutput. The violet pulse emission may reach a level higher than themaximum of the white light emissions (when the violet light source isperiodically OFF). In the example shown, the high level the violet pulseemissions in the occupied room state is not as high as the maximum ofthe white light emissions when the violet light source is periodicallyOFF in that room state. For times of violet pulse emissions in theoccupied room state, the MCU 27 instructs the driver 23 to set maximumamplitude of the high level of the violet pulse emissions and theminimum amplitude of the low level the white violet pulse emissions inthat room state so as combine to produce an overall luminaire outputintensity at or slightly below a combined intensity corresponding to themaximum total drive power available from the driver 23, as representedby the dashed horizontal line. Similarly, in the unoccupied room state,the MCU 27 instructs the driver 23 to set maximum amplitude of the highlevel of the violet pulse emissions in the unoccupied room state and theminimum amplitude of the low level the white violet pulse emissions inthat room state so as to combine to produce an overall luminaire outputintensity at or slightly below a combined intensity corresponding to themaximum total drive power available from the driver 23, as representedby the dashed horizontal line.

This coordinated pulsed emission approach takes better advantage of thepower available from the driver 23 during OFF times of the cleansinglight output and may be implemented using a lower power driver than theearlier approach using constant current control for the white light andadding pulsed violet light emissions.

The examples of FIGS. 6 and 7 involved regular repetitive pulsing of oneor both light sources. In typical schemes for controlling perceptiblelight levels using pulse modulation, e.g. pulse width modulation thatcontrols the duty cycle of pulses that are emitted at a frequencytypically above human eye flicker fusion frequency, the pulses aregenerated at a constant frequency and are periodic recurring waveforms.With such control schemes, adjustment of light output amounts caninvolve modulation of the pulse amplitude, frequency, duty cycle, or thelike. As an alternative, the control scheme for either one or both ofthe cleansing light and the white light may utilize a random variationof pulse outputs. FIGS. 8 and 9 depict to example control schemes usingrandom variations.

Consider the cleansing light by way of example, where achieving thedosage involves a cumulative light output (integral of the area underthe pulse signal over time). The pulses need not be regular in timing orshape. A more randomized pulse scheme as in FIGS. 8 and 9 is less likelyto be perceived as flicker than a regular pulsing of a light output,e.g. as used in pulse width modulation.

In FIG. 8, the white light varies between a high intensity level whenthe room is occupied and a low intensity level when the room isunoccupied, based on constant DC current in the two different roomstates, in a manner similar to the example of FIG. 6. In the approach ofFIG. 8, however, the timing and duration of the violet pulses arerandomized over time. The intensity of the violet pulses is higher thanthe intensity of the constant level of light output from the white lightsource, both when the room is occupied and when the room is unoccupied.In the unoccupied room state, however, the intensity of the violetpulses also is higher than the intensity of the violet pulses during theoccupied room state.

The approach represented by FIG. 9 is more analogous to the pulse schemeof FIG. 7, except that the pulse timing and duration are randomized. Inthe example of FIG. 9, during the random ON times of the pulses ofviolet light output, the driver supplies some power to the white lightsource 15 based on a DC bias included in the drive channel outputconnected to the white LEDs 19. In both the example occupied andunoccupied room states, the cleansing light source 17 together withwhite light source 15 provide a combined light output of the luminaire11 at or slightly below the dashed line in the drawing, whichcorresponds to the output intensity achievable in response to themaximum power available from the driver 23. In the approach of FIG. 9,the timing and duration of the violet pulses are randomized over time,and the timing and duration of low-state of the white light pulses arerandomized in a corresponding manner.

It will be understood that the terms and expressions used herein havethe ordinary meaning as is accorded to such terms and expressions withrespect to their corresponding respective areas of inquiry and studyexcept where specific meanings have otherwise been set forth herein.Relational terms such as first and second and the like may be usedsolely to distinguish one entity or action from another withoutnecessarily requiring or implying any actual such relationship or orderbetween such entities or actions. The terms “comprises,” “comprising,”“includes,” “including,” or any other variation thereof, are intended tocover a non-exclusive inclusion, such that a process, method, article,or apparatus that comprises or includes a list of elements or steps doesnot include only those elements or steps but may include other elementsor steps not expressly listed or inherent to such process, method,article, or apparatus. An element preceded by “a” or “an” does not,without further constraints, preclude the existence of additionalidentical elements in the process, method, article, or apparatus thatcomprises the element.

Unless otherwise stated, any and all measurements, values, ratings,positions, magnitudes, sizes, and other specifications that are setforth in this specification, including in the claims that follow, areapproximate, not exact. Such amounts are intended to have a reasonablerange that is consistent with the functions to which they relate andwith what is customary in the art to which they pertain. For example,unless expressly stated otherwise, a parameter value or the like mayvary by as much as ±10% from the stated amount.

In addition, in the foregoing Detailed Description, it can be seen thatvarious features are grouped together in various examples for thepurpose of streamlining the disclosure. This method of disclosure is notto be interpreted as reflecting an intention that the claimed examplesrequire more features than are expressly recited in each claim. Rather,as the following claims reflect, the subject matter to be protected liesin less than all features of any single disclosed example. Thus thefollowing claims are hereby incorporated into the Detailed Description,with each claim standing on its own as a separately claimed subjectmatter.

While the foregoing has described what are considered to be the bestmode and/or other examples, it is understood that various modificationsmay be made therein and that the subject matter disclosed herein may beimplemented in various forms and examples, and that they may be appliedin numerous applications, only some of which have been described herein.It is intended by the following claims to claim any and allmodifications and variations that fall within the true scope of thepresent concepts.

What is claimed is:
 1. A system, comprising: a luminaire, including: (a)a white light source, for general illumination; and (b) a cleansinglight source, configured to emit visible cleansing light of one or morewavelengths that deactivate a bacteria, wherein the emitted visiblecleansing light is combined with a white light emitted from the whitelight source and output from the luminaire; and a controller coupled tothe light sources configured to: (i) control a continuous light emissionfrom the white light source; and (ii) control light emission from thecleansing light source to emit pulses of visible cleansing light atpulse times concurrent with the white light emission from the whitelight source, wherein during each pulse time of emission of a pulse ofcleansing light from the cleansing light source, the controller controlsthe sources white light source and the cleansing light source such thatfor both a human occupied state and a human unoccupied state of a spaceilluminated by the luminaire, an intensity of pulse emission of thecleansing light from the cleansing light source is higher than anintensity of the white light emission from the white light source. 2.The system of claim 1, wherein the cleansing light source is configuredto exhibit a maximum peak in its output spectrum at a wavelength in arange of 380 nm to 450 nm.
 3. The system of claim 2, wherein thecleansing light source comprises one or more 405 nm light emittingdiodes.
 4. The system of claim 1, wherein the white light source isconfigured to emit white light within three Macadam ellipses below thePlankian Locus (black body curve) of the CIE color chart.
 5. The systemof claim 4, wherein the white light source comprises one or more whitelight emitting diodes.
 6. The system of claim 1, wherein each sourcecomprises a plurality of light emitting diodes, and the controllercomprises: a light emitting diode driver having at least two controlchannel outputs, wherein one of the control channel outputs is connectedto drive the light emitting diodes of the white light source and anotherof the control channel outputs is connected to drive the light emittingdiodes of the cleansing light source; and a processor coupled to thelight emitting diode driver.
 7. The system of claim 1, furthercomprising a range sensor coupled to the controller and located todetect range from the luminaire to a surface on which bacteria is to bedeactivated, wherein the controller is further configured to adjust theintensity of pulse emissions of the cleansing light from the cleansinglight source based on the detected range.
 8. The system of claim 1,further comprising an occupancy sensor coupled to the controller andlocated to detect an occupancy or non-occupancy state of the spaceilluminated by the luminaire, wherein the controller is furtherconfigured to adjust the intensity of pulse emissions of the cleansinglight from the cleansing light source based on the detected state. 9.The system of claim 1, further comprising a user interface coupled tothe controller, wherein the controller is further configured to adjustone or more of ON/OFF state of combined light emission from theluminaire, the intensity of pulse emission of the cleansing light fromthe cleansing light source, or the intensity of the white light emissionfrom the white light source, in response to an input received via theuser interface.
 10. The system of claim 1, further comprising acommunication interface coupled to the controller for data communicationwith one or more elements of a lighting system or for communication witha computing device via a wide area network.